The invention relates to a wind power generator, particularly for inland locations.
Wind power plants with a tower, a nacelle supported on top of the tower and a rotor rotatably supported by the nacelle are well known. The rotor is coupled to at least one electric generator which is disposed in the nacelle and which converts the rotation of the rotor into electrical power. Between the rotor and the generator there is generally a transmission which converts the slow rotor speed to a high generator speed.
To this end, it is also known to provide for a branching of the power. Reference is made in this respect to U.S. Pat. No. 6,731,017. This publication shows a rotor connected to a transmission input gear, which drives several counter shaft gears. From the countershafts, pairs of gears drive generators which supply electric power.
During actual operation of a wind power generator varying forces are effective on the rotor blades depending on the locally prevailing wind speeds. Particularly at inland locations, the rotor may be exposed to rapidly changing wind gusts.
The changing wind speeds can easily cause the rotor blades to vibrate. Rotor blade vibrations or oscillations result in torque variations at the hub of the rotor. They can become so large that generator connected to the rotor may, particularly during operation with a low electrical load, have such a momentum that torque reversals may occur in the transmission. Because of the unavoidable play between the tooth surfaces of the engaged gears, this can result in oscillation impacts on the gears which may result in transmission damage.
Also, often variations of the torque and of the angular speed of the hub occur when a rotor blade passes through the culmination point during its rotation. At this point, the gravity based rotor blade bending is reversed because of the change of direction of the gravity force effective on the rotor blade. This induces rotor blade vibrations on hub vibrations, that is speed variations of the hub which lead to variations in the electric power generation and detrimentally affect the power supply quality.
The rotor vibrations may lead to a reduction of the power supply quality. The rotational vibrations occurring at the rotor shaft result in corresponding power oscillations of the generators and ultimately in electric power oscillations.
It is therefore, the object of the present invention to provide an improved wind energy generating installation.